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 Table of Contents  
Year : 2023  |  Volume : 3  |  Issue : 1  |  Page : 154-156

Pseudo-ophthalmomyiasis externa due to Musca domestica (Housefly): A case report

1 Command Hospital, Carriapa Road, Lucknow, Uttar Pradesh, India
2 Pathologist, Dept of Lab Medicine, Command Hospital, Carriapa Road, Lucknow, Uttar Pradesh, India
3 Professor, Dept of Ophthalmology, Command Hospital, Carriapa Road, Lucknow, Uttar Pradesh, India

Date of Submission14-Jul-2022
Date of Acceptance07-Nov-2022
Date of Web Publication20-Jan-2023

Correspondence Address:
Rakesh K Jha
Asst. Professor, Department of Ophthalmology, Command Hospital, Carriapa Road, Neil Lines, Lucknow Cantt, Lucknow, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijo.IJO_1727_22

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Ophthalmomyiasis is infestation of the eye by fly larva which leads to variable clinical presentations depending on the scale of penetration, species of the fly, and the involved ocular framework. A case of accidental external ophthalmomyiasis, who presented with symptoms mimicking of an acute catarrhal conjunctivitis, is being reported, which was managed with prompt mechanical removal of the larva under topical anesthesia along with supportive treatment. The patient had rapid recovery in the follow up with subsequent microbiological taxonomic identification of the retrieved larvae as of Musca domestica (housefly).

Keywords: Housefly, Musca domestica, myiasis, ophthalmomyiasis

How to cite this article:
Jha RK, Manoj G M, Kaushik J. Pseudo-ophthalmomyiasis externa due to Musca domestica (Housefly): A case report. Indian J Ophthalmol Case Rep 2023;3:154-6

How to cite this URL:
Jha RK, Manoj G M, Kaushik J. Pseudo-ophthalmomyiasis externa due to Musca domestica (Housefly): A case report. Indian J Ophthalmol Case Rep [serial online] 2023 [cited 2023 Feb 7];3:154-6. Available from: https://www.ijoreports.in/text.asp?2023/3/1/154/368164

Myiasis is the infestation of live humans and vertebrate animals with dipterous larvae, which at least for a certain period feed on the host's dead or living tissue.[1] Although encountered commonly in animals, it infrequently also infests humans, commonly from the tropical regions, who are involved in agricultural activities and/or animal husbandry activities[1],[2] with predisposing factors of low hygiene standards and chronic debilitating conditions.

Myiasis, based on host-parasite association,[2] is classified firstly as, obligatory or specific myiasis wherein the parasite needs a host to complete its life cycle; secondly as facultative or semi-specific myiasis wherein the free-living parasite initiates myiasis opportunistically by using necrotic organic matter of open wounds of a host as its breeding ground; and lastly as accidental myiasis or pseudomyiasis wherein the parasites have no preference or need to develop in a host but do so by the accidental deposition either when the gravid female flies come in contact or by the inadvertent swallowing of eggs/larvae.[2],[3],[4]

In humans, the fly families known to cause ophthalmomyiasis are Oesttridae, Calliphoridae, Sarcophagidae, Cuterebridae, and rarely Muscidae[2] with a commonly reported organism being Oestrus ovis.[2],[5] As such, the Musca domestica is an uncommon cause despite the housefly being so common.

Although Musca domestica–associated myiasis in humans has been reported in the eyes,[6],[7],[8],[9],[10],[11] ear,[12] nose,[13] tracheostomy wound,[14] and intestine,[15] literature on accidental Musca domestica–associated human ophthalmomyiasis is fairly limited.[16]

Besides all these cases of ophthalmomyiasis have been reported from the patients, who had either pre-existing local or systemic chronic disability or associated poor nutritional status and hygiene.

To the best of our knowledge, we believe our case to be a rare instance of Musca domestica–associated accidental or pseudo-ophthalmomyiasis in an otherwise healthy patient.

  Case Report Top

A 46-year-old female presented on April 14, 2022, with complaints of foreign body sensation, redness and excessive watering from the left eye since two days following accidental hitting of a fly to her left eye three days ago while riding on the bike as a pillion rider. Immediately, the patient did not perceive any symptoms; however, the next morning she developed the aforesaid symptoms for which initially she went to a local doctor where she was treated as a case of acute viral conjunctivitis. However, her symptoms worsened over the next few days and she sought our care.

Ophthalmic examination revealed visual acuity of 6/6 unaided in both eyes. There was no history of diabetes mellitus or any chronic illness. Conjunctiva was moderately congested with profuse lacrimation in the left eye. Pupils, extraocular movements, and confrontation fields test were normal. Lacrimal sac was clinically patent and intraocular pressure was normal in both eyes. Slit-lamp evaluation revealed two motile larvae which were 1–2 mm long, translucent, white, slender, had a tapered anterior end with a black head, with active crawling movements moving freely over the bulbar conjunctiva and avoiding the slit beam light with a tendency to move toward the fornices [[Figure 1], and Video 1][Additional file 1] along with multiple petechial conjunctival hemorrhages and few peripheral corneal epithelial defects in the left eye.
Figure 1: Slit-lamp examination showing fly larva on the bulbar conjunctiva with multiple punctate conjunctival hemorrhages in the left eye

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Possible presence of larva in the fornices, anterior and posterior segment of the left eye and the contralateral eye was excluded by the detailed clinical examination including double eversion of the upper eyelids. Based on the above, provisional diagnosis of pseudo-ophthalmomyiasis externa left eye was established along with photographic documentation of the subject's clinical picture. The patient was informed about the presence of larvae and advised to undergo mechanical removal, for which consent was taken. The two larvae were removed using a plain fine forceps under topical anesthesia and isolated larvae were sent for the species identification. A copious saline irrigation of the conjunctiva and fornices, exposed by the double eversion of the upper eyelids, was done followed by prescription of topical antibiotics, ointments, and topical steroids.

The ear, nose, and throat (ENT) specialist consultation was sought and revealed normal findings. The relevant radiological imaging was carried out which also excluded ophthalmomyiasis interna/orbital myiasis.

The patient was reviewed on the next day, wherein the patient was still symptomatic and the examination of which revealed the presence of two more similar motile larvae in the superior conjunctival fornices in the left eye, which were removed similarly. The fornices were re-exposed using double eversion of upper eyelids, and copious irrigation along with additional gentle scraping of the exposed surface by cotton swab-sticks was performed.

The nasolacrimal ducts and right eye were re-examined for presence of additional larva. The patient was reviewed consecutively for the next three days, a week later, and after two weeks which excluded any further presence of larvae or secondary complication with resolution of symptoms and signs within the first week.

The unstained larvae on light microscopic examination using 40× magnification were identified as first instar larval stage of Musca domestica (housefly) [Figure 2].
Figure 2: The retrieved organism on microscopic examination was identified as (a) first-instar larval stage of Musca domestica (housefly) with 11 body segments with many brown hooks; (b) characterized by a pair of sharp dark brown oral hooks instead of the head capsule which are used to scrape off food and direct it to the mouth cavity; (c) a pair of spiracles at the posterior end, which are dark sclerotized plates

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  Discussion Top

The housefly is a common inhabitant of human dwellings. The female lays approximately 500 eggs in batches of about 100 eggs on decaying organic matter. The larvae hatch out within 24 hours with a full-grown larva being 8–12 mm long with creamy-white appearance and cylindrical shape and tapered head. The larval stage undergoes three stages of development called “instars” lasting 6–8 days, during which they are parasitic to humans.[2]

Symptoms of pseudo-ophthalmomyiasis are non-specific in early stages and mimic symptoms of viral or bacterial conjunctivitis and hence pass unnoticed especially if the patient profile is from an urban setup with optimal hygiene status and absence of any chronic debilitating conditions; this thereby leads to delayed diagnosis with progression of the case to cause orbital destruction, blindness, and even death.[7],[9],[10],[11] In early stages, it is amenable to simple manual forceps removal of the larvae but in late stages there arises the need to perform complex surgical procedure that ranges from iridectomy, LASER photocoagulation, vitrectomy, retinotomy to even evisceration, enucleation, and exenteration.

Our case stresses for keeping an index of suspicion in all cases of red eye, as it is amenable to candid and effectual treatment in early stages. Furthermore, even if the symptoms evident to be trivial, daily follow-up of patient with thorough examination of fornices especially by the double-eversion of eyelids in the first week are crucial to exclude the existence of any additional larvae or prevent complications. Additionally, the larvae, being highly motile, may escape during the first examination and hence a second re-examination after the initial mechanical removal should be performed after a brief interval rather than sending the patient back in order to relocate and remove additional larvae that may have been missed, as in our case. Furthermore, gentle scraping of exposed forniceal and palpebral conjunctiva should be done as sometimes the larvae may cling to the surface with their hooks and escape removal with irrigation, as in our case.

The imaging of the orbit, paranasal sinuses, and brain should also be considered early if deemed necessary. Besides, recognition of the retrieved larval species is of paramount significance for assessing the probability of globe penetration based on larval invasiveness. Lastly, it highlights the importance of wearing protective eye gear or helmet with visor-on while driving and that even trivial insect encounters with the eye should also be subjected to early ophthalmologist consultation.

  Conclusion Top

An index of suspicion for pseudo-ophthalmomyiasis should be kept while treating any case of acute red eye. A thorough examination of fornices, especially by the double eversion of upper eyelids, is of crucial importance to ensure detection of hidden larvae. A second re-examination after a brief period following initial removal on the same day is recommended to detect additional larvae that may have escaped during initial examination. Post-traumatic pseudo-ophthalmomyiasis by Musca domestica (housefly) is rare, but early diagnosis and apt management can offer a prompt clinical recovery and prevent complications.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Zumpt F. Myiasis in Man and Animals in the Old World: A Textbook for Physicians, Veterinarians and Zoologists. London: Butterworth Co Ltd; 1965.  Back to cited text no. 1
Fabio F, Omar L. Myiasis. Clin Microbiol Rev 2012;25:79-105.  Back to cited text no. 2
Garcia-Zapata MTA, de Souza Júnior ES, Fernandes FF, Santos SFO. Human pseudomyiasis caused by eristalis tenax (Linnaeus) (Diptera: Syrphidae) in goiás. Rev Soc Bras Med Trop 2005;38:185-7.  Back to cited text no. 3
Borkovcova M, Vesely P. Pseudomyiasis with connection to organic waste - first case reported in Czech Republic. Acta Univ Agric Silv Mendel Brunensis 2008;56:19-24.  Back to cited text no. 4
Grammer J, Erb C, Kamin G, Wild M, Riedunger C, Kosmidis P, et al. Ophthalmomyiasis externa due to the sheep botfly Oestrus ovis in Southwest Germany. Germ J Ophthalmol 1995;4:188-95.  Back to cited text no. 5
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  [Figure 1], [Figure 2]


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